Spark plug



June 5, 1934. A, KEGRESSE 1,962,078 I SPARK PLUG Filed Aug. 19, 1930 2 Sheets-Sheet 1 Fig.1

A. KEGREssE June 5, 1934.

SPARK PLUG Filed Aug. 19, 1930 2 Sheets-Sheet 2 Patented June 5, 1934 i v UNITED STATES PATENT oFFlca SPARK PLUG Adolphe Kegrcssc, Courbevoie, France Application August 19 1930; Serial Dim/476,391

In France September 19, 1929 4 Claims. (01. 123-169) One is aware that the compression ratio in 2 is formed at the base thereof with a seat internal combustion engines, particularly those 3 which tightly fits the wall 4' of the combustion of the four-stroke cycle type, is limited by selfchamber. The seat 3 is held in position by ignition. means of a nut 5 screwed on the outside of the 5 This phenomenon is one of the causes by upper portion of the body 2 and bearing tightly which a limit is set to motor efliciency. It is in against the upper wall 7 of the water jacket. most a es e to t p k plu s. the coolin The walls 4 and '1 of the water jacket 9 are oi! which is insufliciently provided for. braced to each'other by ribs 8. An additional nut One is aware also that the plugs inengines of 10 screwed within the upper portion of the body 10 conventional type are screwed in bosses formed 2 holds the insulation 1 in-position. In order to 65 on the casing and that consequently the cooling secure a maximum cooling efiect for the elec- Of the p k p will take place th ough the trodes where the sparks are set up, the base Walls O the boss and the body of the p gportion of the body 2 is formed with a cir- There is thus provided a double layer of metal, cular neck 11.

one at least of which is the result of a casting It will e appreciated t t as a mt of t e 70 operation. considerable thinness of the plug body walls,

W. Pa u y with eel o the kind prevathe shape given thereto and the heat conduclently used for the manufacture of cylinder tiveness of the metal selected, a'maximum cooldfi, it is not Possible to Obtain t Walls ing effect is obtained. Since the body 2 of the ufil n ly thin n strong to Secure the plug is independent of the cylinder head, the 5 s d maximumcoolihg fi plug can be machined very easily. and conse- In addition, cast steel is not the best metal quently the w n th reof can be made as thin as far as heat conductivity is concerned. A as the t ughness of the metal will allow. distinct advantage would therefore be gained in t is likewise t b t d th t the whole porfinding out a more conductive metal to provide ti adjacent to the spark spaceis also cooled 80 f p spurp s s- I very greatly inasmuch as this portion is wholly s i v t has its jfi fl 8- nOVel constituted by the circular neck 11, whereby this a a t 0! the p Plugs according region is brought as close as possible to the wh c t insulatiOh i housed in 8 p body of cooling water. Heat exchange is thus member or plug body having thin heat-com ilit t d,

ductlve walls which are in direct contact with According to the modification shown in Figs. the o g-fl (Water depending On t 3 and-i, the outer walls 2 and the base portion type of engine considered). I 3 of the plug body. instead of being plain as is An embodiment of the invention is Shown by the embodiment just described, are provided 3 Wall 0 example in the p y g drawin s. with ribs 2 and 3' intended to increase the sur- 9 V wherein: Figure 1 is a vertical cross sectional race of contact with the cooling water, thus vi w h u h a p k plu in ac rd nc wi h securing a more intense cooling street on the my invention plug.

Figure 2 is a horizontal cross sectional view In the case shown in Figs. 5 and 6 in which 40 taken on l ne I in F the engine comprises no cooling water jacket, 5 Figure 3 is a vertical cross section of a modithe head is formed with props 8 corresponding fication. to. the bracing ribs in Figs. 1 and 3, the said Figure 4 is a cross section taken on line props allowing the plug to be secured in po- IV--IV in Fig. 3. sition. This embodiment is given only by way Figure 5 is a vertical cross sectional view of of indication and may be substituted by any 9. modification embodied in an air-cooled enother that will allow the plug body to remain ginein contact with the surrounding air. The cen- Figure- 6 is a cross sectional view taken on .tral electrode is separated from the atmosphere line VI--VI in Fig. 5. only by one single layer of metal, viz., the hol- 50 Figure 7 is a modification of the embodiment low body 2' with or without its ribs 2', whereby shown in Fig. 5. a maximum cooling effect on the plug is secured The embodiment shown in Fig. 1 will first as in the case of the water-cooled engine. be described. In the modification shown in Fig. '7, the

The insulation 1 of the plug is housed in a body 2 of the plug is integral with the cylinder 55 suitably shaped thin-wall body 2. The said body head. Ribs 2' are formed on the body for cooling purposes. The insulation 1 of the central electrode is housed within the body 2 as in the arrangement according to Figs. 1, 2, 3, 4, 5 and 6.

The bottom portion of the plug body is formed with a neck 11 the purpose of which is to reduce to a minimum the distance between the centre of production of the sparks and the su rounding air.

The embodiments described hereinbefore are not of limitative character and may lend themselves to all desirable constructional modifications without thereby departing from the scope of the invention.

I claim:

1. In combination with an internal combustion engine, a wall surrounding and spaced from the walls of the combustion chamber to form a water jacket, an opening through the wall of the combustion chamber and the wall of the water jacket, and a spark plug having a casing seated in the opening, the spark plug comprising a hollow body having, thin conductive walls, the walls being in direct contact with the cooling water, said casing having an extensive circular neck at its lower end which forms a continuation of the wall of the combustion chamber, the neck having a small opening to receive the point of the spark plug.

2. The combination set forth in claim' 1, wherein the circular neck has projecting ribs for the purpose of increasing heat conductivity.

3. In combination with an internal combustion engine, a wall surrounding and spaced from the walls of the combustion chamber to produce a water jacket, openings through the walls of the combustion chamber and the wall of the water jacket to receive a spark plug, the opening through the wall of the water jacket being smaller than that through the wall of the combustion chamber so that the spark plug must be inserted first through the opening in the combusion chamber, a spark plug seated in the openings, and means fastened to the spark plug and adapted to draw it from the combustion chamber toward the water jacket so as to seat the plug tightly, said spark plug comprising a tubular casing element extending through the opening in the jacket wall and having a flared skirt-like flange seated in the opening in the combustion chamber wall and forming a continuation of the combustion chamber wall, said casing having a restricted portion immediately adjacent the flared skirt-like flange, and an insulated electrode positioned in the tubular casing and having a portion extending through the restricted portion of the casing which serves as an electrode, said casing being formed of thin heat conductive metal and being in direct contact with the water in the cooling jacket, whereby the spark plug and the portion of the wall of the combustion chamber surrounding the plug constituted by the flange of the casing will be maintained at a lower temperature than the rest of the cylinder wall.

4. In combination with an internal combustion engine, a casing surrounding and spaced from the Walls of the combustion chamber to provide a water jacket, an opening through the wall of the combustion chamber and the outer wall of the water jacket a spark plug seated in the opening, said spark plug comprising a tubular casing element extending through the opening in the jacket wall and having a flared skirt-like flange seated in the opening in the combustion chamber wall and forming a continuation of the combustion chamber wall, said casing having a restricted portion immediately adjacent the flared skirt-like flange, and an insulated electrode positioned in the tubular casing and having an uninsulated portion extending through thy restricted portion of the casing which serves as an electrode, said casing being formed of thin heat conductive metal and being in direct contact with the water in the cooling jacket, whereby the spark plug and the portion of the wall of the combustion chamber surrounding the plug constituted by the flange of the casing will be maintained at a lower temperature than the rest of the cylinder wall.

ADOLPHE KEGRESSE. 

